Prosthetic hip replacement is an operation designed to replace a hip joint that is damaged either due to trauma or some type of degenerative disease such as osteoarthritis. The hip is a joint made up of a bone sphere located at the proximal end of the femur, the femoral head, which is located within a cavity in the hip bone to which it adjusts perfectly. Hip prosthesis may comprise replacing the femoral head and/or the acetabulum. If the femoral head is replaced, the prosthesis further comprises a stem, which is inserted into the femur.
Currently, in most of the total systems of implanted hip prostheses, the stem is metallic (chromium-cobalt, stainless steel or titanium) mainly due to the high mechanical stresses that must be supported by said component once it has been implanted. The femoral head can be made of chromium-cobalt or some kind of ceramic material. As regards the acetabular component of the hip prosthesis, also known as acetabular cup and which is placed directly on the pelvis, the most widely used proposal today is composed of an ultra high molecular weight polyethylene body (UHMWPE) embedded inside a metal sheath, generally made of CoCr or titanium alloys with rough finishes in order to improve the anchoring thereof with the hip bone.
The use of UHMWPE in the acetabular cup requires the use of the metal sheath in order to fix this component to the bone, since the UHMWPE does not possess the osteointegrating capacity of other materials such as titanium after the application of certain preparation and/or treatment techniques. In spite of everything, sometimes this sheath can be loosened as a result of lack of bone fixation to the titanium cup. This is one of the main causes of failure in this type of component, which requires replacing the cup, provided that there is sufficient bone available for the replacement.
The clinical success of prostheses or implants used in bone tissue replacement is based on achieving osseointegration, i.e., the direct structural and functional connection between ordered, living bone and the surface of the implant. The improvement of short and long-term osseointegration is a function of multiple factors, among which the surface quality of the implant (physico-chemical and topographic) is of great importance. In fact, all the biological and mechanical interactions that occur between the implant and the surrounding tissues are through the interface created between said tissues and the surface of the implanted material.
Document U.S. Pat. No. 6,596,225 describes the use of diamond ceramic surface coatings deposited by means of PVD techniques, the main purpose of which is to increase the surface hardness of articulation surfaces in order to reduce the wear thereof. The ceramic nature of the diamond coating described in this document provides a bioinert nature to the coated surface, unlike the acetabular component of the present application, which provides a bioactive nature to the surface of the coating, which ensures the osseointegration thereof and the adherence thereof to the hip bone.
On the other hand, document EP0608997 describes the use of zirconium oxide ceramic surface coatings deposited by means of PVD techniques, the main purpose of which is to increase the surface hardness of articulation surfaces in order to reduce the wear thereof as well as improving corrosion resistance of the assembly by providing a barrier against the release of ions from these coatings.
Therefore, the purpose of the present invention is to provide a prosthesis component that improves the fixation thereof, based on the formation of a bioactive layer in order to improve the degree of osseointegration and, therefore, the fixation thereof to the bone.